Reducing paper tubes in diameter



June 12, 1951 w. F. STAHL- REDUCING PAPER TUBES IN DIAMETER Filed Oct. 1, 1945 Patented June 12, 1951 .UNITED STATES PATENT OFFICE 3 Claims.

This invention relates to reducing a paper tube in diameter and more particularly to the reducing in diameter of laminated or spirally wrapped paper tubes. In the practice of the invention a portion only of a tube may be reduced so that the finished tube has a portion of larger diameter and a portion of reduced diameter.

Laminated paper tubes are ordinarily formed by wrapping an adhesive covered paper strip spirally upon itself to form a tube.

ioned into different types of products, such as cores for windings of insulated wire, etc.

tube having one portion thereof relatively large The tube may then be cut in the various lengths and fash- F some uses, it is important to have an integral and another portion of reduced diameter. At-1 I An object of the present invention is to provide a simple method by which a portion of a laminated paper tube may be quickly reduced in diameter while at the same time remaining rel-' atively strong and having a smooth exterior. A further object is to provide a method whereby a spirally wrapped paper tube may be reduced in diameter in such a manner as to cause the creases or wrinkles therein to run uniformly in a longitudinal direction thereby reinforcing the structure against transverse bending and also providing over the longitudinal creases and wrinkles a top skin or layer which is relatively free from wrinkles and which forms with the longitudinal creases and ribs a sturdy product. Another object is to provide an improved paper tube having a. portion of relatively large diameter merging with a portion of relatively small diameter, the portion of relatively small diameter, together with the connecting portion, being reinforced with an outer skin portion which combined with the longitudinal creases in the body of the reduced portion of the tube results in a tube of relatively strong cross section. Other specific objects and advantages will appear as the specification proceeds.

The invention is illustrated, in a preferred embodiment, by the accompanying drawing, in which- Figure 1 is a perspective view of a tube product formed in accordance with my invention; Fig. 2, a longitudinal sectional view of the structure shown in Fig. 1; Fig. 3, a side view in elevation, and partly in section, of apparatus employed in the carrying out of my new method, a portion of a paper tube being shown on the apparatus and in position'prior to the reducing operation; Fig. 4, a view similar to Fig. 3 but showing the tube in reduced condition after the spinning operation; Fig. 5, a greatly enlarged plan view of a small part of the inside of the reduced portion of the tube l2; and Fig. 6, a greatly enlarged cross sectional view of a portion of the tube, the section being taken as indicated at 6-6 of Fig. 5.

In the illustration given in Figs. 3 and 4, l0 designates a mandrel which may be maintained in fixed position. The mandrel is provided at its forward end with an inwardly stepped portion ll receiving the spirally wrapped paper tube [2. If desired, the member ID may be provided with a further reduced portion l3. l4 designates the rotatable chuck in which is secured a spinning tool I 5. The tool I5 is hollow in its forward portion and provided at its front with a bevel I 6 which may be of any suitable angle. In the illustration iven, the angle of the bevel is approximately 30 and, in common practice, such an angle has been found very satisfactory. It will be understood, however, that considerable variation in the angle may be made in the handling of diiTerent qualities of paper tube stock.

In the operation ofthe structure shown in Figs 3 and 4, the operator places the tube l2 in position upon the reduced portion I I, as shown in Fig. 3, and then while holding his finger upon the end portion of the tube near the body It) in order to prevent rotation of the member l2, the chuck I4 is advanced while it is being rapidly rotated. This movement brings the beveled edge l6 into contact with the forward end of the tube l2. Under the rapid rotation of the member IS, the tube [2 is reduced in diameter at its forward end and a product like that shown in Fig. 4 results from the operation. The rapid spinning of the member l5 produces considerable heat, and

the heat is effective also in producing the smooth exterior of the tube.

Under the efiect of the rapidly rotating member l5 as the beveled edge I6 advances against the tube l2, there is formed in the body of the tube l2 a number of longitudinal channels or creases or wrinkles IT, as indicated more clearly in Fig. 5, running lengthwise of the tube. There are relatively no creases or wrinkles which extend in directions other than the longitudinal direction indicated. The result of the forming of such longitudinal creases is to increase the strength of the tube against transverse strain. In addition to the forming of the creases in the body of the material, the ironing efiect of the rotating member l5 produces a smooth skin portion IS on the outer surface of the tube. The skin IB bridges the longitudinal wrinkles or creases or ribs and provides a relatively smooth outer surface. The enveloping of the ribbed structure by the smooth skin body [8 produces a resultant tube structure highly resistant to transverse strain and to longitudinal strain. I do not know all the factors that enter into the forming of the new skin surface; the heat generated through the rotation of the member [5 seems to give a, glazin effect which unifies the outer surface while at the same time the ironing efiect of the member I5 seems to bring about a rematting or change of direction of the fibers, so that they substantially bridge the grooves or creases to provide an outer skin that is relatively free of wrinkles and extremely smooth.

In the structure shown in Fig. l, the tube i2 is provided with a reduced portion It and the ends of the tube are pressed inwardly at [9 to lock the disks in position. The foregoing structure is merely illustrative of one use to which the tube, having different diameters, may be put. It will be understood that such a tube having two portions of varying diameter may be employed in a great variety of products.

In the construction of the member l5 and particular-ly the beveled edge i5, it is important to use a high speed tool steel, and I prefer a highly polished tool steel. Such a tool operates effectively in reducing the diameter of the tube while at the same time rematting the fibers and producing a truly round reduced tubular portion of a glazed or shiny surface. It will be noted as indicated in Figs. 3 and 4 that the reduced diameter of the tube may be brought about without employing an inner support for the reduced portion. The spinning edge IE which is gradually pressed against the tube is effective in itself in producing the reduced diameter of the tube and its new physical structure.

While in the foregoing specification, I have set forth certain details of structure and method for the purpose of illustrating one mode of the invention, it will be understood that such details may be varied widely by those skilled in the art without departing from the spirit of my invention and further that the claims herein should be 4 looked to as definitive of the scope of the invention.

I claim:

1. The method of reducing the diameter of a portion of a paper tube, comprising rotating a tubular edge having a diameter less than that of the tube and with an enlarged beveled mouth against said tube to reduce the diameter of the tube while forming longitudinally-extending valleys therein, and supporting the inner walls of the tube against rotation about the point of junction between the tube portions of different diameters while the beveled mouth ofsaid edge irons the supported connecting portion between said tube portions of diiierent diameters.

2. In a method for reducing the diameter of a portion of a laminated paper tube, the steps of pressing a longitudinal portion of the tube inwardly to reduce the diameter thereof and while forming longitudinal valleys therein, supporting against rotation the inner walls of the tube about the point of junction between the tube portions of different diameters, and simultaneously ironing the tube portion of reduced diameter to form thereon a smooth outer tube portion free of valleys.

3. In a method for reducing the diameter of a portion of a laminated paper tube, the steps of pressing a longitudinal portion of the tube inwardly to reduce the diameter thereof and while forming longitudinal valleys therein, supporting against rotation the inner walls of the tube about the point of junction between the tube portions of diiferent diameters, and simultaneously ironing the tube portion of reduced diameter and the connecting portion joining it to the tube portion of larger diameter to form a smooth outer tube portion free of valleys.

WILLIAM STAHL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 441,836 Greenfield Dec. 2, 1890 1,018,473 Auchu Feb. 2'7, 1912 1,384,945 Ford July 19, 1921 1,673,993 Parker June 19, 1928 1,983,361 Gazette Dec. 4, 1934 2,266,420 Gardner Dec. 16, 1941 

